Method of calendering a plastic mass



June 11, 1957 B. B. BLACKFORD 2,795,521

METHOD OF VCALENDE RING A PLASTIC MASS Filed June 5, 1953 ATTORNEY tiresheet.

United States Patent 2,795,521 METHOD. OF CALENDERING A PLASTIC MASSBenjamin B. Blackford, Metuchen, N. J., assignor to Johnson & Johnson, acorporation of New Jersey Application June 5, 1953, Serial No. 359,701

3 Claims. (Cl. 154-102) The invention is directed to spreading ofadhesive on webs in parallel strip zones leaving parallel uncoated zoneson the web between the coated zones. Particular embodiments of theinvention are directed to preparation of such zone coated webs for useasbacking material for surgical dressings, and in particular, adhesivebandages.

Backing sheets utilized in ordinary adhesive bandages are coated with anadhesive mass which covers the eu- In many instances merely to assurefirm anchorage of the bandage to the patient it is not necessary to coatthe entire surface of the backing with adhesive, and therefore economywithout sacrifice in quality would be realized by coating the backingmaterial with adhesive in zones or strips. In other cases, to produceproper venting of the adhesive bandage it is necessary to perforate thebacking in the region of the dressing pad, whereas if regions of thebacking were left uncoated with adhesive the natural permeability of theuncoated backing sheet would afiord sufficient venting without thenecessity and additional expense of perforation. Hence, one object ofthe invention is to produce a sheet zone-coated with adhesive which maybe used in manufacture of adhesive bandages with particular advantagefrom the standpoint of economy and improved venting characteristics.

Prior art zone coating procedures have been carried out on the order of'Gilchrist U. S. P. 2,086,126 which requires the use of raised portionsof metal on the roll itself which pick up adhesive from a kiss roll anddeposit this adhesive from the raised portion directly onto the web.There are many disadvantages to this type operation among which are thenecessity of specialized, highcost equipment, and the tendency of theraised portions on the roll to wear excessively due to direct contactwith the kiss roll.

One object of the present invention is to develop a procedure andmachinery for zone coating of adhesive on moving webs which is simpleand inexpensive and does not involve the use of specialized high-costequipment.

According to'the present invention, coated and uncoated longitudinalzones are calendered on a continuous web of material by feeding adhesivemass between a pair of adjacent rolls, one of the rolls having raisedportions on its periphery and adjacent the other roll, the raisedportions being spaced axially from each other. The raised portions onthe one roll do not, however, touch the other roll. Said other rollrotates, and the temperature of the rolls is controlled to control inturn the plasticity of the adhesive so that said raised portions, as theadhesive is drawn as sheet or film between the rolls, cause the adhesivefilm to divide into separate, longitudinal sections which aresubsequently deposited on a continuous sheet of material to formlongitudinal coated and uncoated zones thereon. The raised portions onthe first roll correspond and are substantially coextensive with theuncoated zones of material and, conversely, the unraised portionscorrespond and are substantially coextensive with the coated zones. Itis a particularly notable feature of the invention that division of theadhesive film ice between the rolls and resulting uncoated zones on thefab r-ic are produced without having the'surfaces of the-two rollsforced together or in contact. This is accomplished as indicatedutilizing a suitable adhesive so that at theternperature of theoperation the plasticity of the adhesive is:

sufiiciently low so that the adhesive film divides spontaneously when itpasses between the raised portionsof the. one roll and the second roll.The invention also includes the apparatus for carrying out the operationdescribed. v

In addition to accomplishing the objects set forth above, the advantagesof the invention include provision of method and means for manufactureof a product wl n'ch may be made more economically, since it containsless adhesive than the usual calendered product, and also has thedesirable property of permittingsome passage'of water vapor so that inuse as a backing for adhesive bandages it is not necessary to perforatethe backing to pro-' vide for breathing of the bandage. y

The invention may be conveniently understood by ref erence to theattached drawing in which the same reference number referstocorresponding parts of the various figures.

Fig. l is a side elevation view of a three roll calender constructedaccording to the invention.

Fig. 2 is a front elevation of the apparatus in Fig. 1'.

Fig. 3 illustrates the top two rolls of Figs. 1 and 2 constructedaccording to a'modifiedform of, the invention.

Reference number 10 designates a supporting frame for a three rollcalender having a top roll 11, a middle roll 12 and a bottom roll 15,respectively. The-top roll is supported on axle 16, the middle roll onaxle 17 and the bottom roll on axle 20, each axle being supported inframe 10. Ear blocks 21 and 22 disposed at opposite ends of the top andmiddle rolls serve to guide adhesive into the nip between these tworolls. Feed roll 25 contains a wind-up of sheet material which may befabric, non-woven or woven, or may be synthetic material'suc'h asregenerated'cellulose.

Top roll 11 is provided on its periphery with a spiral winding ofmaterial 27 such asa sturdy thread of textile fibers anchored at eachend to roll 10 or to-fram e 10 at points not shown. Band 27 may benarrow or wide, as will appear hereinafter, depending upon whether it isdesired to have narrow or wide areas of uncoated material in the finalproduct. It will be noted that therolls 11 and 12 are not in-contact,but that there is a finite-space designated as A in Figs. land2 separating these two rolls at the nip 23. A notable feature of thisinvention is that the band of material '27 does not fill-in'all of thespace A but leaves a small but finite clearance between the outermostlimits of band 27 and the topmost surface of roll 12. The importance ofthis feature of the invention apparatus will appear hereinafter. Y

The apparatus is operated as follows. An adhesive mass having suitableplasticity and other properties given below is placed in a bank betweenear blocks 21 and 22 and the nip between rolls 11 and12.' 'Rolls 12 and15 are rotated in the direction indicated in Fig. 1, while roll 11remains stationary. Alternatively, roll 11 may rotate slowly in whichcase band 27 may suitably be secured to roll 11 itself rather than toframe 10. *The adhesive from bank 30 tends to be drawn into and out ofthe nip between rolls 11 and 12 as a thin sheet 31 having a smoothsurface and uniform thickness depend ing upon the clearance A betweenthe rolls. "The temperature and speed of the rolls are controlled'asthey are in normal calender operations. Near the point where rolls 11and 12 are closest to contact, the filmof adhesive 31 from bank 30 isdivided or split by the raised portion 27 of the-band into individualfilms 31 which travel around the left side of roll 12 as seen in Fig. 1and into the nip 32 between rolls1-2-and 15. At this point theindividualsheets of adhesive -31-on thesurface of roll 12 meet andcontact the upper surface of fabric 26. The adhesive adheres to thesurface of fabric 26 and leaves the periphery of roll '12. Theindividualareasof adhesive coated on fabric 26 are shown at on Fig. '2 withparallel uncoated areas of adhesive therebetween at 36. It willbelnotedthat-the-uncoated areas 36 correspond and aresubstantiallycoextensivein width-with the band material 27 in the -nip'between rolls 11 and-12.

To provide the. splitting and dividing action by ridges 28 on roll'll itis importantthat, if roll his not stationary,it should move at 'a ratewhich is slower than the rateof movement of the film 31 emerging fromthe nip'23. Movementof rollll may beclockwise or counterclockwise. 'Itisimportant only thatanyclockwise directional movement. should be slowerthan that corresponding witha peripheral speed equal tothe speed ofmovement, of, film31. .Inthe modified embodiment of the inventionillustrated in Fig. 3 top roll40 and middle roll 41 are shown with spaceA therebetween. ,These rolls are supported on axles 45 and46 mounted ina frame not shownsimilar to frame 10 in Fig.2. Instead of band ofmaterial-27 woundspirally around thetop roll, roll 40 is provided withindividual bands 47 secured to roll 40 by means not shown.Theseindividual bands 47in the nip between rolls 40 and 41 perform afunction corresponding to those portions of. band .27 in the mp2sbetween rolls Hand 12. .The width,uspacing,. height and clearancebetween the rolls is :controlled in theFig. .3 embodiment in the sameway a nd ffor thesamepurposesas in vthe vease of the; Fig. -2embodirnent describedabove.

The material of-which the band is made is a factor of considerableimportancem thepresent invention. It is preferably made of a materialsofter. than that of the su'rfaceof roll 12. This affords the'advantagethat in the case of inadvertent contact :betweenband 27 ,and roll- 12there will be no or little wearbetween the parts in contact,;.and inparticular, no wear of the surface of roll 12,:therebynecessitatingrebuilding of the equipment, or at the very least, expensivemaintenance. The bands maybe made suitably of either fabric or metal orother material. *Thevheight of the band-is also important. As indicated;above, it doesnotpcome in contact with the. outer-surface of roll ;12.vHowever, it, should be sufficientlyrhighto cause:splittingor-dividingof the film of adhesive from .bank 30 in theregionof ip; 23. :With this :objectin view the vheight of-band-27 shouldbe atleast. about onehalf the dimension A, i.; e. ;one, half :the distancelbetween'rollsill and 12 .at nip.23. It is seen, therefore,.thatthezdepth. of;.groove .24 which is equal to the height of .ridges.28 .is preferably at .least about as :great-as thefinitedistanceibetween the radial. eX-

trernity ofridges. 28 and the'sadjacentsurface of roll 12/ Theplasticity of the .adhesivemass in .bank 30 will be influenced by thetemperature. of T011511 and .12, -.the degree of working onthe rollscontrolled in turn by the roll speed, and the internal'friction broughtabout .by this working. The tendency of the adhesive film from bank-.30to divide'into separate longitudinal areas as described above isinfluenced to a degree by this plasticity.

Accordingly, in the present invention the nature of the mass-is suchasto afford under-operating conditions a mass plasticity sufliciently high.to produce the desired dividing of the film.

It is not alwayspredictable from the mass plasticity at room temperatureor at any given temperature what the plasticity ofthe mass will be as itisbeingworked-in the bankcon the calender rolls. However, suitablemasses forgone coating. according tothe invention may be madebycompounding approximately equal parts of 'elastom-er,taekifierzandzextender. The .elastomer may. benatural rubber,butadiene-slyrene :copolyiner, reclaimed:rubber, onpolyisobutylene fillstomer. ;-Mix t ures of these various elastomers may be employed. Anyof various tackifiers known in the art, may be satisfactorily utilized.iExtenders, as the term is used here, includes also fillers andpigments. Zinc oxide, titanium dioxide, and starch are examples ofingredients falling in this classification. In addition to the abovethree groups of ingredients the adhesive may also be plasticized withany of several plasticizers known in the art.

According to preferred embodiments. ofthe invention, the masses are socompounded that their plasticities measured under standard conditions oftest are ,within a certain preferred: range. 'Plasticityissmeasured on acylindrical pellet of .adhesivemass 16 mm. in diameter and weighing 2.00grams. By placing the pellet on a parallel plate plastometer of. thetype manufactured, for example, by the Scott Instrument Company, andmaintaining the pellet and surroundings at F. and under a 5000 gram loadfor 14 minutes, the height in millimeters of the pellet-after this timeis taken ,as .a measurement' of plasticity. The preferred plasticity.range} is,.approximately 1.5 to 2.5mm. Howeverylower or higherplasticities may beused depending uponthebehav'ior of the'adhesive whenit is subjected to the conditions prevailing in the bank-between thecalender rolls.

' One satisfactory adhesive mass is composed of.polyisobutylene-according to Wing U. S.-P. 2,484,060, preferably withan average molecular weight (staudingeryofabout 100,000 compounded witheffective. amounts :of tackifier, plasticizer, pigment,--etc.- asdisclosed in-the patent. *For purposes of theprese'nt -invention,.-it ismilled for time to impart plasticity oft-.5 to- 2.5 mm.

Another suitable ma'ss is-based-on natural pale -crepe rubber" (33%) andcontains dehydro'genated rosin acid MJP. '70-72 C., tackifier (25%),lanolin (7%) -as plasticizen'TiOa (15%) and Z (15%) aspigment,--a'ndstarch (5%) as filler, and is milled'fortime toprovide a plasticity offrom'1;5 to 2.5 mm. Blends of-the-syn thetic and natural rubbers may beutilized.

The following is an example of procedure-for manufacture of azone-coatedfabric particularly suitable for use as a backing for adhesive bandages.'A'web 10f woven material having a count of 80x 80' per inch and aweight of 3 ounces per squareiyard isunrolled from roll 25 and fediintothe nip between rolls 12 and 15.

* An adhesive massflhavingithe composition describedin the nextpreceding. paragraph and 1a plasticity of 1.70 ispreheated to 240 F. andcharged to jbankj. 30 from which it is fed into nip 23 betweengste'elv,rollsf 11 and 12. Roll.11 is operated at 250 F. and. ro1l, 12' at F.thereby. to maintain bank 30 at laboutl240" 'F. The spacing betweenrolls I1 and 12 is 0.004 inch. ;Roll 11 is wound on its outsideperiphery. with an bqagor copper wire having asquare brossf section10.003 vinch thick and 0.020 inchwide. The .winding is ,arranged in aspiral fashion andsecured at-the two ends tofstationary par'ts offramelt). Said copper ;ribbo n-;forms ridges28. (With the windinginplace the distance be tween ridges. 28. is- Vz inch. The height ofridges 28 above the surface. of roll 11 ;is.0.003 inch and the, width ofeach ridge is:0..020 inch. ,Roll v11-.isstationary;;and roll12;rotates;at-.a peripheral speed of QO -feet' per. minute. The massdivides into-separate individual sheets 35 with intervening parallelzones of no adhesive. The product as itiswithdrawn from-roll lS containsparallel coated zones /2 inch wide and intervening uncoated Zonesapproximately inch wide. The adhesive strip moves with rotation ofroll'l2'fromnip 23 to thdbot tom of roll 12 where contactv is madewithfthe upper surface of fabric 26. The fabric picks up the adhesivestripswhich become embedded in fabric 26. 2

Various modifications and equivalents which will now be apparenttogthose skilled in theart, .although;,-not specifically recited above,are. intended to be included within the scope of the invention. It-isintended that the invention be limited, not by the above disclosure, butonly by the appended claims as fairly interpreted in view of thedisclosures of the prior art.

The claims are:

1. A method of calendering a pressure-sensitive adhesive mass having aplasticity at 100 F. in the range of about 1.5 to 2.5 mm. and comprisinga tackifier and an elastomer, the latter being selected from the groupconsisting of natural rubber, reclaimed rubber, butadiene-styrenecopolymer and polyisobutylene, which method comprises forming arelatively wide film thereof at a temperature of about 240 F., said filmbeing of a thickness of about 0.004 inch, and pressing parallel groovestherein about 0.003 inch deep and about 0.02 inch wide, said groovesbeing about 0.5 inch apart, while moving said film in the direction ofsaid grooves, whereby separate parallel films about 0.004 inch thick andabout 0.5 inch wide are obtained.

2. A method of claim 1 wherein the parallel films are deposited upon acontinuous sheet of material form ing longitudinal coated and uncoatedzones thereon, said uncoated zones being about inch wide.

3. A method of claim 2 wherein the plasticity is about 1.7 mm.

References Cited in the file of this patent UNITED STATES PATENTS1,402,160 Gwozdz Ian. 3, 1922 1,471,588 Bourn Oct. 23, 1923 1,628,836Gammeter May 17, 1927 1,683,707 Smith Sept. 11, 1928 1,974,209 FowlerSept. 18, 1934 2,054,115 Abrams et al. Sept. 15, 1936 2,070,600 JenettFeb. 16, 1937 2,089,525 Abrams et a1. Aug. 10, 1937 2,582,294 StoberJan. 15, 1952 FOREIGN PATENTS 892,998 France May 25, 1944

1. A METHOD OF CALENDERING A PRESSURE-SENSITIVE ADHESIVE MASS HAVING APLASTICITY AT 100*F. IN THE RANGE OF ABOUT 1.5 TO 2.5 MM. AND COMPRISINGA TACKIFIER AND AN ELASTOMER, THE LATTER BEING SELECTED FROM THE GROUPCONSISTING OF NATURAL RUBBER, RECLAIMED RUBBER, BUTADIENE-STYRENECOPOLYMER AND POLYISOBUTYLENE, WHICH METHOD COMPRISES FORMING ARELATIVELY WIDE FILM THEREOF AT A TEMPERATURE OF ABOUT 240*F., SAID FILMBEING OF A THICKNESS AT ABOUT 0.004 INCH, AND PRESSING PARALLEL GROOOVESTHEREIN ABOUT 0.003 INCH DEEP AND ABOUT 0.02 INCH WIDE, SAID GROOVESBEING ABOUT 0.5 INCH APART, WHILE MOVING SAID FILM IN THE DIRECTION OFSAID GROOVES. WHEREBY SEPARATE PARALLEL FILMS ABOUT 0.004 INCH THICK ANDABOUT 0.5 INCH WIDE ARE OBTAINED.
 2. A METHOD OF CLAIM 1 WHEREIN HTEPARALLEL FILMS ARE DEPOSITED UPON A CONTINUOUS SHEET OF MATERIAL FORMINGLONGITUDINAL COATED AND UNCOATED ZONES THEREON, SAID UNCOATED ZONESBEING ABOUT 1/16 INCH WIDE.